rhinencephalon

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

n. The olfactory region of the brain, located in the cerebrum.

from Wiktionary, Creative Commons Attribution/Share-Alike License

n. The part of the brain involved with olfaction.

from the GNU version of the Collaborative International Dictionary of English

n. The division of the brain in front of the prosencephalon, consisting of the two olfactory lobes from which the olfactory nerves arise.

from The Century Dictionary and Cyclopedia

n. The olfactory lobe of the brain; the foremost one of the several morphological segments of the encephalon, preceding the prosencephalon. In the lower vertebrates the rhinencephalon is relatively large, and evidently a distinct part of the brain. In the higher it gradually diminishes in size, becoming relatively very small, and apparently a mere outgrowth of the cerebrum. Thus, in man the rhinencephalon is reduced to the so-called pair of olfactory nerves, from their roots in the cerebrum to the olfactory bulbs whence are given off the numerous filaments, the proper olfactory nerves, which pierce the cribriform plate of the ethmoid, and ramify in the nose. The rhinencephalon, like other encephalic segments, is paired or double—that is, consists of right and left halves. It is primitively hollow or has its proper ventricle, which, however, is entirely obliterated in the adults of the higher vertebrates. This hollow is a prolongation of the system of cavities common to the other encephalic segments, and known as the rhinocœle. Also rhinencephal. See cuts under Petromyzontidæ, Rana, brain (cut 2), and encephalon.

Etymologies

Examples

A group of structures within the rhinencephalon, that part of the brain once thought to be devoted to smell, which is associated with various emotions such as anger, fear, sexual arousal, pleasure, and sadness.

The auditory area occupies the middle third of the superior temporal gyrus and the adjacent gyri in the lateral fissure; the visual area, the calcarine fissure and cuneus; the olfactory area, the rhinencephalon.

The rhinencephalon, associated with the sense of smell, is the oldest part of the telencephalon, and forms almost the whole of the hemisphere in some of the lower animals, e. g., fishes, amphibians, and reptiles.

They were thus regarded as a part of the rhinencephalon, but it is now recognized that they belong to the neopallium; the cingulate gyrus is therefore sometimes described as a part of the frontal lobe, and the hippocampal as a part of the temporal lobe.

"In fact, the seat of many of those emotional centers—the limbic system—was once called the 'rhinencephalon,' literally 'nose-brain' or 'smell-brain.' A 2003 study found that strong smells triggered activity in both the amygdala and the ventral insula."—Steven Johnson, The Ghost Map (New York: Penguin, 2006), 128